502 MR. A. SMITH WOODWARD ON EXTINCT [Mar. 17, 
directed process. The left maxilla (mwx.) is completely preserved, 
slightly arched in form, with a small ascending process near its 
anterior end, and a little expansion posteriorly. Of the right 
maxilla only a fragment of the anterior end remains, The pre- 
maxille are not shown, but the bone labelled “? barbel axis” in 
Cope’s original specimen may be one of them. No teeth are 
exhibited in any part of the mouth. The preoperculum (p.op.) 
has-a large lower limb and is much expanded at the angle. The 
operculum (op.) is imperfect above, but evidently trapezoidal in 
form and somewhat deeper than broad. The suboperculum (s.op.) 
is deeper behind than in front, and exhibits four deep clefts in the 
lower half of its hinder border. Small scales can be observed 
enveloping all the head and opercular bones. 
The vertebral centra are much constricted and strengthened 
with small irregular longitudinal ridges. The ribs are remarkably 
slender, apparently supported by stout processes frum the centra ; 
while the separate neural spines in the anterior half of the 
abdominal region are expanded into thin narrow lamine. The 
last vertebra of the tail (Pl. XVIII. fig. 2) bears an upwardly-turned 
double style, and there are seven expanded hemal arches at the 
base of the caudal fin, the lowest apparently connected with the 
penultimate vertebral centrum, the next three with the last 
centrum, and the upper three with the terminal style. It is also 
worthy of note that the neural arch in the three vertebre pre- 
ceding the last is forked from the base. Intermuscular bones are 
seen above the vertebral column throughout, and below it in the 
caudal region. . 
The fins are as described by Cope, except that the pelvic pair is 
much larger than indicated in the original specimens. The scales 
are precisely similar in shape and denticulation to those of the 
existing Gonorhynchus. 
2. NoroconEus squamMossEvs. (Plate XVIII. figs. 3, 4.) 
1818. Cyprinus squamosseus, H. D. de Blainville, Nouv. Dict. 
d@’Hist. Nat. vol. xxvii. p. 371. 
1844. Sphenolepis squamosseus, L. Agassiz, Poiss. Foss. vol. v. 
pt. i. p. 13, pt. i. p. 87, pl: xlv. 
Formation and Locality. Upper Eocene; Aix-en-Provence, France. 
The so-called Cyprinus or Sphenolepis squamosseus is represented 
in the British Museum by several specimens, which, taken together, 
display nearly all its essential characters. The head with opercular 
apparatus is relatively much larger than in Notogoncus osculus, its 
length exceeding the maximum depth of the trunk, and contained 
only about four times in the total length of the fish; the vertebral 
centra are also much shorter ; otherwise its specific characters seem 
to be identical with those of the American fish. 
The best-preserved head belongs to a specimen wanting part of 
the abdominal region and the caudal fin, and is shown of two- 
thirds the natural size im Pl. XVIII. fig. 3. It is unfortunately 
very imperfect, but the enveloping small scales (s.) are exposed 
in a narrow band, both above and below. The much-fractured 
